If $a + 5b = 1$ and $x + 8y + z = 2$, what is $-x + 45b - 8y + 9a - z$ ?
Answer: $= 9a + 45b - x - 8y - z$ $= (9) \cdot (a + 5b) + (-1) \cdot (x + 8y + z)$ $= (9) \cdot (1) + (-1) \cdot (2)$ $= 9 - 2$ $= 7$